Among the various video display systems available in the art, an optical projection system is known to be capable of providing a high quality display in a large scale. In such an optical projection system, light from a lamp is uniformly illuminated onto an array of, e.g., M.times.N, actuated mirrors such that each of the mirrors is coupled with each of the actuators. The actuators may be made of an electrodisplacive material such as a piezoelectric or an electrostrictive material which deforms in response to an electric field applied thereto.
The reflected light beam from each of the mirrors is incident upon an aperture of a baffle. By applying an electrical signal to each of the actuators, the relative position of each of the mirrors to the incident light beam is altered, thereby causing a deviation in the optical path of the reflected beam from each of the mirrors. As the optical path of each of the reflected beams is varied, the amount of light reflected from each of the mirrors which passes through the aperture is changed, thereby modulating the intensity of the beam. The modulated beams through the aperture are transmitted onto a projection screen via an appropriate optical device such as a projection lens, to thereby display an image thereon.
In FIG. 1, there is shown a cross sectional view of an M.times.N electrodisplacive actuated mirror array 10 for use in an optical projection system, disclosed in a copending commonly owned application, U.S. Ser. No. 08/278,472, entitled "ELECTRODISPLACIVE ACTUATED MIRROR ARRAY", comprising: an active matrix 11 including a substrate 12 and an array of M.times.N transistors thereon; an array 13 of M.times.N electrodisplacive actuators 30, each of the electrodisplacive actuators 30 including a pair of actuating members 14, 15, a pair of bias electrodes 16, 17, and a common signal electrode 18; an array 19 of M.times.N hinges 31, each of the hinges 31 fitted in each of the electrodisplacive actuators 30; an array 20 of M.times.N connecting terminals 22, each of the connecting terminals 22 being used for electrically connecting each of the signal electrodes 18 with the active matrix 11; and an array 21 of M.times.N mirrors 23, each of the mirrors 23 being mounted on top of each of the M.times.N hinges 31.
In the above mentioned copending, commonly owned application, there is also disclosed a method for manufacturing such an array of M.times.N electrodisplacive actuated mirrors, employing a ceramic wafer having a thickness of 30 to 50 .mu.m.
There is room for further improvements over the above described method for manufacturing an array of M.times.N electrodisplacive actuators, however. First of all, it is rather difficult to obtain a ceramic wafer having a thickness of 30 to 50 .mu.m; and, furthermore, once the thickness of the ceramic wafer is reduced to a 30 to 50 .mu.m range, the mechanical properties thereof are likely to degrade which may, in turn, make it difficult to carry out the manufacturing process.
In addition, it involves a number of time consuming, hard to control, and tedious processes, thereby making it difficult to obtain the desired reproducibility, reliability and yield; and, furthermore, there may be a limit to the down sizing thereof.